1. Field of the Invention
This invention relates to a hollow cathode gun (hereinafter referred to as HCD gun) used in the ion plating through a hollow cathode discharge (HCD) process, and more particularly to an HCD gun for high ionization and large deposition having good discharge properties and long life as well as a deposition device for iron plating which enables to formation of a deposit film having improved uniformity and bonding property in the ion plating through the HCD gun.
2. Related Art Statement
Ion plating utilizing a plasma is applied to ceramic coating of TiN, TiC, Ti(CN) and the like. As ion plating processes, there are practised HCD process, a combination of EB (electron beam) and RF (radio frequency) processes, the multi-arc process, the arc discharge process and so on. Among these processes, the HCD process is widely utilized for ceramic coating of TiN, TiC, Ti(CN) and the like because the ionization ratio is as high as 20.about.60% and the film-forming rate is as relatively fast as 0.05.about.0.5 .mu.m/min. Particularly, the HCD process has an advantage that the ceramic coating can easily and smoothly be carried out even when slightly changing various factors such as flow rate of N.sub.2 gas, vacuum degree, bias voltage, substrate temperature, pretreatment of substrate and the like.
Ion plating through the HCD process is elucidated, for example, in Metal Surface Technology, 35[1], pp 16.about.24 (1984) and Powder and Powder Metallurgy, 32 (1985), pp 55.about.60.
Since the hollow cathode for plasma generation used at the present in the HCD gun is made from Ta, the durable life per gun is only about 100.about.150 hours and use exceeding this life is impossible for ceramic coating, so that such a gun is very expensive (400,000.about.1,000,000 Japanese yen per gun) and accounts for about 30.about.50% in the coating cost. Therefore, it is desired and demanded to develop a cheap HCD gun capable of stable use over a long period of time.